The development of minimally invasive methods and devices over recent years has revolutionized the practice of medicine. These methods and devices allow clinicians to perform a wide variety of procedures while minimizing trauma to the patient. A wide variety of treatment devices that utilize minimally invasive technologies has been developed, and includes stents, stent grafts, occlusion devices, perfusion catheters, drainage catheters, drug delivery systems and endoscopes.
In many minimally invasive devices, a sheath surrounds an inner component, such as a stylet or trocar. Together, these components are navigated through a body lumen to a point of treatment. Once this point is reached, the clinician may need to manipulate these and other components relative to each other to achieve the goal of the treatment. For example, the clinician may need to move a sheath relative to an inner trocar to allow sampling of a tissue for a biopsy.
In these techniques and devices, it is important to have an ability to control this relative movement in the components. For example, if a trocar has a sharp edge, it may be necessary to maintain a sheath over the trocar during navigation. Also, it may prove beneficial to have control over the precise length by which an inner component, such as a trocar, extends distantly beyond another component, such as a sheath.
In some procedures, several components, such as a sheath and a trocar, are used in combination with another medical device, such as an endoscope. In these procedures it may prove helpful to control the amount by which the sheath extends beyond a distal end of the endoscope.